Machines for pinch-pointing metal screws



Aug. 27, 1968 E. J. SKIERSKI 3,393,413

MACHINES FOR PINCH-PC'INTING METAL SCREWS Filed Sept. 20, 1967 2Sheets-Sheet 1 FIG.!

INVENTOR EDWIN J. SKIERSKI 6 BY )M fi hula/2 ATTYS.

United States Patent 3,398,413 MACHINES FOR PINCH-POINTING METAL SCREWSEdwin J. Skierski, Wayne, N.J., assignor to Parker- Kalon Corporation,Clifton, N.J., a corporation of Delaware Continuation of applicationSer. No. 475,533, July 28, 1965. This application Sept. 20, 1967, Ser.No. 675,999 2 Claims. (Cl. 16-9) ABSTRACT OF THE DISCLOSURE A machinefor pointing the pilot end of a metal screw blank having means forprecisely locating a pair of complementary dies and for guidingly movingthe dies into an operative position. The dies are constructed to preventcontact between the work faces thereof during operation of the machine.

The present invention relates to machines for pinchpointing the pilotends of metal screw blanks prior to threading of the substantiallycylindrical shanks thereof; and it is a general object of the inventionto provide such a machine of improved and simplified construction andarrangement. The present application is a continuation of my copendingapplication for United States Letters Patent Ser. No. 475,533, filedJuly 28, 1965, and now abandoned.

Another object of the invention is to provide a pinchpointing machine ofthe character noted that is characterized by high-speed operation so asto increase significantly the number of blanks that are pointed duringeach time interval of operation thereof.

A further object of the invention is to provide a pinch pointing machineof the character noted that employs a pair of complementary dies thatare mounted for selective relative movements with respect to each otherand between a fixed open position and a fixed closed position, whereinthe dies respectively carry a pair of mating work faces that aredisposed in close proximity to each other with a predetermined clearancetherebetween when the dies occupy their fixed closed position, andwherein the dies respectively carry a pair of mating abutments thatdirectly engage each other in the fixed closed position thereof toestablish the predetermined clearance mentioned.

A further object of the invention is to provide a machine of thecharacter noted, wherein each of the dies is formed of an extremely hardmaterial, such as a metal carbide.

A still further object of the invention is to provide a machine of thecharacter described, wherein the dies are respectively removably carriedby a pair of die holders that are mounted for guided selective relativemovements toward and away from each other, so as correspondingly to movethe dies into their respective fixed closed and fixed open positions.

Further features of the invention pertain to the particular arrangementof the elements of the pinch-pointing machine, whereby the aboveoutlined and additional operating features thereof are attained.

The invention, both as to its organization and method of operation,together with further objects and advantages thereof, will best beunderstood by reference to the following specification, taken inconnection with the accompanying drawings. It is to be understood thatthe specific embodiment of the invention shown in the drawings andhereinafter described in the specification is for illustration purposesonly and is not to be construed as a limitation of the invention. Moreparticularly, it is to be clearly ice understood that dies havingvarious cavity or recess configurations may be employed withoutdeparting from the scope of this invention.

In the drawings:

FIG. 1 is a side elevational view, of a metal screw blank that is to bepointed at the pilot end thereof prior to threading of the shankthereof;

FIG. 2 is a side elevational view of the screw blank following pointingof the pilot end thereof and preceding the threading of the shankthereof;

FIG. 3 is a top perspective view of a pair of dies that are removablycarried in a pinch-pointing machine for working the screw blank of FIG.1 to produce thescrew blank of FIG. 2;

FIG. 4 is a plan view of the pinch-pointing machine incorporating thedies of FIG. 3 and embodying the present invention;

FIG. 5 is an enlarged vertical sectional view of the dies in theirpartially open position, this view being taken in the direction of thearrows along the line 5-5 in FIG. 4; and

FIG. 6 is another enlarged vertical sectional view, similar to FIG. 5,of the dies in their fixed closed position.

Referring now to FIG. 1 of the drawings, the screw blank 10 thereillustrated may be formed of steel, and essentially comprises anenlarged head 11 of any desired form and a substantially cylindricalshank 12. Prior to threading of the shank 12, the pilot end thereof isordinarily pointed, as indicated at 13, and as illustrated in FIG, 2.This pointing of the pilot end 13 of the shank 12 is effected in thepresent instance utilizing the dies 21 and 31, as shown in FIG. 3, andemploying the pinchpointing machine 59, as shown in FIG. 4. AlthoughFIG. 2 illustrates a screw blank having a conically pointed pilot end,FIG. 3 illustrates dies for forming a conical pilot end and thediscussion to follow will be limited to the use of the present inventionto manufacture a screw having a conical pilot end, it is to beunderstood, and is considered obvious, that various other pilot endconfigurations may be formed utilizing the present invention simply byappropriately altering the die recess or cavity as for example byproviding projections within said die recess to form tapping surfaces inthe pilot end.

In the operation of the dies 21 and 31, the pilot end 13 is produced ina pinching step with the removal of scrap, as indicated at 14, from theextreme outer end of the shank 12, and without substantial longitudinalelongation of the shank 12. In the blank 10, after the formation of thepilot end 13, the angle between opposed lines along the cone-shapedpoint or pilot end 13 may be approximately 45, as indicated in FIG. 2.Thereafter, the blank 10 of FIG. 2 is subjected to a threading step, notherein involved; and, specifically, the thread mentioned may be formedin the shank 12 in a thread-rolling step, involving suitablethread-rolling dies, not shown.

Referring now to FIG. 4, the pinch-pointing machine there illustrated,and embodying the features of the present invention, comprises astationary head 51, a movable head 52, and facility mounting the head 52for guided movements toward and away from the head 51, this facilityincluding a ram, indicated generally at 53. A block 54 is detachablysecured to the stationary head 51, and a block 55 is detachably securedto the movable head 52. The block 54 carries a pair of laterally spacedapart guide bushings 56, and the block 55 carries a pair of laterallyspaced-apart guide pins 57; which guide bushings 56 receive the guidepins 57 so as accurately to guide the longitudinal movements of theblock 55 toward and away from the block 54. An upstanding recess 54a isformed in the central portion of the block 54 for the purpose ofsupporting the die 21, and an upstanding re cess 55a is formed in thecentral portion of the block 55 for the purpose of supporting the die31. The die 21 is accurately located along the center line of the block54 and within the recess 54a by substantially U-shapeddie holder 61including a pair of laterally spaced-apart arms 62 and 63. The die 21 isprecisely locatedwithin a die pocket 65 in the die holder 61 in intimatecontact with the rear surface of the die pocket, the side of the diepocket formed by a surface of the arm 62 and the lower surface of thedie pocket which is formed by the lower surface of the recess 54a.Intimate contact with said surfaces of the die pocket 65 is establishedby the cooperative action of a conical recess 24x in the die 21 and aclamping screw 64, as hereinafter discussed in detail. This structurefacilitates accurate, easy location of .the die 21 along the center lineof the block 54. In a similar manner, the die-31 is accurately locatedalong the center line of the block 55 and within the recess 55a by asubstantially U-shaped die holder 71 including a pair of laterallyspaced-apart arms 72 and 73 which form a die pocket 75 in cooperationwith the rear portion of the holder 71 and the lower surface of therecess 55a. Precise location of the die 31 is accomplished in the samemanner as the die 21. In the arrangement, the die holder 61 nicely fillsthe recess 54a in the block 54, and the die holder 71 nicely fills therecess 55a in the block 55.

Before proceeding further with the description of the construction ofthe machine 50, reference is made to FIG. 3, wherein the dies 21 and 31are illustrated as being complementary, each being of elongated form andhaving a substantially rectangular lateral cross-section. Specificallythe die 21 comprises a forwardly disposed work face 22, and a top side23 and a front side 24 illustrated. Similarly, the die 31 comprises aforwardly disposed work face 32, and a top side 33 and a front side 34illustrated. A substantially cone-shaped recess 24x is formed in thefront side 24 of the die 21; and a substantially cone-shaped recess 34xis formed in the front side 34 of the die 31. A pair of mating recesses22a and 32a are respectively formed in the top central portions of themating work faces 22 and 32; which recesses 22a and 32a are arranged inregistry with each other; and each of these recesses has a substantiallysemiconical configuration in the illustrated embodiment. The surfaces ofthe work face 22 are cut-away on opposite sides and below the recess22a, as respectively indicated at 24a, 24b and 240; and, similarly, thesurfaces of the work face 32 are cut-away on opposite sides and belowthe recess 32a, as respectively indicated at 34a, 34b and 340. A deepclearance recess 25 is formed in the central portion of the work face 22and positioned below the surface 24c; and, similarly, a deep clearancerecess 35 is formed in the central portion of the work face 32 andpositioned below the surface 340. Finally, in the illustrated embodimenta generally triangular shaped abutment 26 is formed on the lower portionof the work face 22; and, similarly, a generally triangular-shapedabutment 36 is formed on the lower'porin the dieholder 61. Specifically,the extreme front end of the clamping screw 64 is substantiallycone-shaped and is adapted to engage into the recess 24x formed in thefront side of the die 21. As illustrated in FIG. 4, the axis of theclamping screw 64 is offset from the. axis of the conical recess 24xwhen the screw 64 is in an operative position. More specifically, asviewed in FIG. 4, the axis of the clamping screw 64 is offset to theleft of and with respect 'to the dieholder -61-an'd quick clamping inprecise location of the die '21 when it is disposed in its mountedposition in the dieholder 61. In a similar manner, a clamping screw 74is carried in a nicely fitting opening formed in the front section ofthe block 55; which clamping screw 74engages a cooperatingthreaded'opening provided in the front arm 73 of the dieholder 71 andprojects therethrough into cooperating clamping'relation with theadjacent die 21- in its supported'position in the dieholder 71.Specifically the extreme front end of the clamping screw 74 issubstantially cone-shaped and is adapted to engage intothe recess 34xformed in the front side of the side 31. The axis of the clamping screw74 is-oflset from the axis of the conical recess 34x when the screw 74is in operative position. That is, again as viewed inFIG. 4, the axis ofthe clamping screw 74 is to the right of and below or downwardly fromthe axis of the conical recess 34x. Thus, when the clamping screw 74 isadvanced, the cone-shaped forward end thereof eccentrically engages theconical recess 34x and urges the die 31 rearwardly, downwardly andlaterally into intimate contact with the rear, lower and a side surfaceof the die pocket 75. Thus the screw'74 is selectively operative betweenclamping and releasing positions with respect to the die 31 so as to,accommodate ready placement and removal of the die 31 with respect tothe dieholder 71 and quick clamping in precise location of the die 31when it is disposed in its mounted position in the dieholder 71.

Again referring to the dies 21 and 31 of FIGS. 3, 5 and 6, it is notedthat they are formed of a material that is extremely hard and .that hasa hardness number on the Vickers scale in the general range 1300 to1400. A suitable such material is a sintered metal carbide alloy, such,for example, as tungsten carbide. This commercial material usuallycontains a small amount of tantalum carfbide or titanium carbide.Frequently, the commercial alloy contains about 87% to tungsten carbideand about 5% to 13% tantalum carbide or titanium carbide, or acombination of both tantalum carbide and titanium carbide, all byweight. The use of dies formed of material having a hardness of thismagnitude requires precise alinement of the dies during operation. Ithas been found that unless the dies are exactly alined, substantial,immediate damage thereto will result. This is particularly true wheredies havingotherthan asemiconical recess such as illustrated are used.That is, if.for example, projections are provided in the die recess toform cutting or tapping surfaces on the pilot end of a screw blank, theprojections will be shattered or cracked if the dies are not preciselyalined. The cooperation of the guide bushings 56 and guide pins57 andthe clamping screws and conical recesses in the dies for exactlylocating the dies with repetitive uniformity ensure alinement therebyfacilitating the use of such di es. p

In the operation of themachine 50, the ram 53 is operative toreciprocate the block 55, so as to move the block 55 toward and awayfrom the block 54; and which movements are guided by the guide pins 57sliding in the guide bushings 56. As previously. noted,the pair of guidepins 57 are carried by the block 55,-and the-pair of guide bushings 56"are carried by the block 54. Thus, the die 31 carried by the 'block 55is movedinan accuratelysguided path toward and away from the. die 21carried by the block ,54 Specifically, the die 31 is m o,ved between afixed closed position, shown in FIG, 6, with'respectto the die 21 and afixed open position, substantially shown in FIG. 5, with respect to thedie 21. More particularly, the die 31 is slightly displaced toward theright with respect to the, die 21 from its position as shown in FIG. 5,when the die 31 occupies its fixed open position. The fixed openposition of the dies 21 and 31, is established by the movement of theblock 55 into its extreme right-hand position as set by the action ofthe ram 53. On the other hand the fixed closed position of the dies 21and 31 is established by the abutments 26 and 36 respectively carried'by the work faces 22 and 32 of the dies 21 and 31. Specifically, whenthe dies 21 and 31 are in the closed position thereof, as shown in FIG.6, the abutments 26 and 36 directly engage each other, so as to preventstriking of the surfaces 24a, 24b and 240 and the corresponding surfaces34a, 34b and 340 and so as to establish the predetermined narrowclearance, indicated at in FIG. 6, between the dies 21 and 31 in theirclosed position, as shown in FIG. 6.

Further, the machine 50 comprises in the illustrated embodiment, asshown in FIG. 4, an air blast nozzle 81 carried by the rear section ofthe block 54 and directed toward the dies 21 and 31 in their closedposition, the nozzle 81 serving to direct a stream of air under pressureinto the dies 21 and 31 in order to insure the removal of the scrap 14from the pilot end of the blank 10 in the pinching of the cone-shapedpoint 13 in the illustrated embodiment on the extreme outer end of theshank 12, as best illustrated in FIG. 6. Also, the machine 50 com prisesany conventional facility, not shown, for feeding the blanks 10successively into the dies 21 and 31 in coordinate relation with themovements thereof between their open and closed positions.

Considering now the operation of the machine 50 to effect pinch-pointingof the blank 10, and referring to FIGS. 5 and 6, it is noted that whenthe dies 21 and 31 are in their open position, one of the blanks 10 isdropped by the feeding facility into the dies 21 and 31. Specifically,the extreme front end of the shank 12 is dropped into a fixed workposition between the recesses 22a and 32a respectively formed in theupper portions of the work faces 25 and of the respective dies 21 and31, as clearly shown in FIG. 5. The die 31 is then moved from its fixedopen position towards its fixed closed position, both with respect tothe die 21; whereby the extreme outer end of the shank 12 is firstclamped in its work position between the dies 21 and 31 at the apex ofeach of the semiconical recesses 22a and 32a. Continued closing movementof the die 31, pinches the button-like scrap 14 upon the extreme lowerend of the shank 12, while forming the cone-shaped point 13 on the pilotend of the shank 12, and without substantial longitudinal elongation ofthe shank 12, all as shown in FIG. 6. In the fixed closed position ofthe dies 21 and 31, as shown in FIG. 6, the abutments 26 and 36 areengaged, with the clearance 20 between the marginal edges of thesurfaces 24a, 24b and 240 and the marginal edges of the surfaces 34a,34b and 340. In the illustrated embodiment, the small shock produced bythe impact of the abutments 26 and 36 breaks the scrap 14 from theextreme lower end of the shank 12 and at this time a blast of compressedair is directed from the nozzle 81 into the dies 21 and 31, so as toblow the scrap 14 clear of the dies 21 and 31. The dies 21 and 31 arethen moved toward their full open position and the blank 10 is movedforwardly from between the dies 21 and 31 with the result that the blank10 falls between the die holders 61 and 71 and is caught below theblocks 54 and 55 to be further worked in the thread-rolling step, thatfollows the present pinch-pointing step. When the die 31 is again movedinto its fixed open position, another blank 10 is fed into the dies 21and 31 in the manner explained above.

In the machine 50, the arrangement, wherein the abutments 26 and 36respectively carried by the dies 21 and 31 directly engage or strike asthe die 31 is moved into its closed position with respect to the die 21,is very advantageous, since it positively establishes the smallpredetermined clearance 20 between the boundary edges of the recess 22aand 32a in the respective dies 21 and 31 so as to insure breaking off ofthe scrap 14 from the extreme outer pilot end 13 of the shank of theblank 10 when a conical point is being formed on the blank. Moreover,the abutments 26 and 36 are not deformed or battered during use of thedies 21 and 31 over an extremely long useful life, since the dies 21 and31 are formed of the exceedingly hard material, and the dies 21, 31 arelocated in precise alinement in the die pockets 65, 75 and are guidinglymoved by the cooperative action of the bushings 56 and pins 57.Furthermore, the abutments 26 and 36 are not shattered in the operationof the dies 21 and 31, notwithstanding the fact that the dies 21 and 31are formed of the extremely hard material, as noted above.

Also, the arrangement of the clamping screws 64 and 74 and thecooperation thereof with the respective die holders 63 and 73 and withthe respective dies 21 and 31 is very advantageous, since the sameaccommodates ready placement and removal of a plurality of pairs of diesin the recesses 54:: and 55a in the respective blocks 54 and 55, asrequired in the manufacture of a series of screws of different sizes, asrequired in the marketing of such screws. As noted above, the clampingscrews 64, 74 and conical recesses 24x, 34x ensure uniform alinement.

In a constructional example the dies 21 and 31, in the manufacture ofscrews of the size numbers 6, 8 and 10, each die may have a length of1.000", a height of 1.000 and a width of 0.500". The recesses 22a and32a may have the respective diameters 0.124", 0.144" and 0.160"respectively corresponding to the screw size numbers 6, 8 and 10. Theclearance 20 between the dies 21 and 31 may be in the general range0.003" to 0.004"; and the other dimensions may bear the relations tothose noted of the parts set forth in accordance with the scales ofFIGS. 3, 4, 5 and 6. Employing the dies 21 and 31 of the characternoted, the machine 50 has an operating speed in excess of of that ofconventional pointing machines and is operated to work in excess of 600screw blanks per minute.

In view of the foregoing, it is apparent that there has been provided amachine for pinch-pointing the pilot end of the shank of a screw blank,which machine is of improved and simplified arrangement andincorporating a pair of dies for the pinch-pointing step that are ofimproved and simplified construction and arrangement.

While there has been described what is at present considered to be thepreferred embodiment of the invention, it will be understood thatvarious modifications may be made therein, and it is intended to coverin the appended claims all such modifications as fall within the truespirit and scope of the invention.

Having thus described my invention what I claim as new and desire tosecure by Letters Patent of the United States is:

1. A machine for pointing the pilot end of a metal screw blankcomprising a stationary mounting member having a plurality of spacedguide bushings extending outwardly therefrom, a movable mounting membermovable linearly between a fixed open position and a fixed closedposition with respect to said stationary mounting member, said movablemounting member having a plurality of guide pins extending outwardlytherefrom and slidingly received Within said bushings whereby accuratelyto maintain alignment of the movable mounting member relative to thestationary mounting member during movement thereof, die holding andlocating means associated with each of said mounting members,complementary dies located in said die holding means associated withsaid mounting members, said die holding means having die locatingsurfaces for precisely positioning said dies in a predetermined locationwhereby to ensure exact alignment of said complementary dies when saidmounting members are moved into said fixed closed position, each of saiddies having a conical recess formed in a side thereof, means forclamping said dies in precise location in said die holding means inintimate contact with said die locating surfaces comprising clampingscrews mounted in said mounting members and having conical forward endscomplementary to said conical recesses in said dies, the axes of saidclamping screws being oifset from the axes of the conical recesses insaid dies when said dies are located in operative position in said dieholding means whereby said dies are forced into intimate contact withsaid die locating surfaces when the conical end of said clamping screwis urged into eccentric engagement with the conical recesses in saiddies, a pair of mating work faces respectively carried by said dies anddisposed in close proximity to each other with a predetermined clearancetherebetween when said dies occupy said fixed closed position, a pair ofcomplementary recesses formed in said work faces and arranged inregistry with each other when said dies are clamped in said die holdingmeans, the pilot end of a screw blank being readily insertable into awork position disposed between said work faces and into cooperatingrelation with said recesses 8., 7 when said dies occupy said fixed openposition, movement of said dies into said fixed closed position firstclamping therebetween the pilot end of a screw blank in its workposition and then pinching a point on the pilot end of the screw havinga configuration complementary to the configuration of said die recesses,anda pair, of mating abutments respectivelycarried by said dies anddirectly engaging each other in said fixed closedposition to establishsaid predetermined clearance between said work faces in said fixedclosed position.

2. A machine according to claim 1 wherein the dies are formed ofsintered metal carbide.

References Cited UNITED STATES PATENTS 6/1936 Horton 10 2,4

LEONIDAS VLACHOS, Primary Examiner. 7

